I just sent Apple an email about this. We will see what they say. My gut is that this has something to do with whatever spam filtering they have. I think any brand that allows users to write reviews these days has a tough job on their hands in terms of fighting fake reviews. If your app is new or the reviews are coming from devices with very little history, I wonder if Apple does not count them or removes them when stronger reviews come in with more history. It's confusing, for sure, and the lack of transparency on Apple's part is annoying. At the same time, if they open up publicly with their exact methodology, it will be easier for people to spam it, so I partially understand.